DNA amplification by the polymerase chain reaction for the rapid diagnosis of tuberculous meningitis. Comparison of protocols involving three mycobacterial DNA sequences, IS6110, 65 kDa antigen, and MPB64

Abstract

DNA amplification of three Mycobacterium tuberculosis-specific DNA sequences by the polymerase chain reaction (PCR) were evaluated as a means for rapid diagnosis of tuberculous meningitis (TBM). The DNA sequences amplified were a 123 bp region of the IS6110 insertion elements which occur in multiple copies in the mycobacterial genome, a 240 bp region (nts 460–700) from the MPB 64 protein coding gene, and the 383 bp region of the 65 kDa heat shock protein (HSP) antigen. Twenty-seven cerebrospinal fluid (CSF) specimens were studied. Six were obtained from patients with TBM diagnosed by culture ( 4 6 ) or by the patients' response to anti-tuberculous therapy ( 2 6 ). The remaining 21 specimens were obtained from patients with febrile seizures ( 3 21 ), aseptic meningitis ( 3 21 ), septic meningitis ( 14 21 ), and cryptoccocal meningitis ( 1 21 ), and these served as negative controls. Our results indicate that although the protocols involving the 3 DNA sequences were able to detect TB DNA in the 6 TBM specimens, the main drawback was their extreme sensitivity, thus giving rise to false positive results. In particular, the repeat copy sequence, IS6110, and the 65 kDa HSP gave unacceptably large numbers of false positive results (62% and 33%, respectively).